Production of dineo-dicarboxylic acids

ABSTRACT

Di - neo acids are produced by treating an anhydride of a monocarboxylic acid, which anhydride contains at least one carbon atom bearing a tertiary hydrogen atom separated from the neo acid group by at least two carbon atoms, with strong acid.

United States Patent Yeomans [ll] 3,715,392 1 Feb. 6, 1973 [541PRODUCTION OF DINEO- DICARBOXYLIC ACIDS [75 Inventor: Betram Yeomans,l-lessle, England [73] Assignee: B P Chemicals Limited, London,

England 22 Filed: Jan. 16, 1970 21 Appl.No.: 3,535

[30] Foreign Application Priority Data Feb; 10'; '1' 939 Great Britain..7,056/69 [52] US. CL. ..260/537 R, 260/413, 260/546 [51 Int. Cl ..C07c51/00 [58] Field of Search ..260/537 R Primary Examiner-Vivian GarnerAttorney-Jacobs & Jacobs [57] ABSTRACT Di neo acids are produced bytreating an anhydride of a mono-carboxylic acid, which anhydridecontains at least one carbon atom bearing a tertiary hydrogen atomseparated from the neo acid group by at least two carbon atoms, withstrong acid.

6 Claims, N0 Drawings The present invention relates to the production ofdineo carboxylic acids. In this specification by a neo-acid is meant acarboxylic acid in which the alpha carbon atom is attached to fourcarbon atoms.

The present invention is a process for the production of a di-neocarboxylic acid by treating the anhydride of a mono neo carboxylic acid,which anhydride contains at least one carbon atom bearing a tertiaryhydrogen atom, separated from the neo carboxylic acid group by at leasttwo carbon atoms, with strong acid.

The anhydride may be a mixed anhydride or it may be formed from twomolecules of the same acid, when it will contain a carbon atom bearing atertiary hydrogen atom in each carbon chain. In any event it ispreferred that the anhydride contains at least two such carbon atoms,one in each chain.

The mono neo carboxylic acid from which the anhydride is preparedpreferably contains from nine to 20 carbon atoms, and consequently theanhydride preferably contains 18 to 40 carbon atoms. The carbon atomsbearing the tertiary hydrogen atom and the neoacid group are separatedby at least two, preferably at least four carbon atoms. If the acidcontains more than one such carbon atom the nearest one should be atleast two, preferably at least four carbon atoms from the acid group.

The anhydride may be prepared by any of the conventional methods forproducing anhydrides, for example, by reaction with ketene or aceticanhydride or by heating the acid at about 250C to 350C.

The acidic substance may be a Bronsted or a Lewis acid, preferably witha pK value greater than 2, such as hydrofluoric, perchloric,chlorosulphonic, fluorosulphonic or phosphoric or sulphuric acid. Thepreferred acid is concentrated sulphuric acid, which should be at least90% w/w, preferably at least 97% w/w. Nitric Acid should not be used asoxidation reactions may occur. Preferred Lewis acids are pentafluoroantimonate in admixture with hydrofluoric acid, boron trifluoride inadmixture with phosphoric acid or boron trifluoride in admixture withhydrofluoric acid.

Not less than 1 mole of acid should be used per mole of anhydride. Thepreferred amount is 5 to moles of acid per mole of anhydride, when usingsulphuric acid. With mixtures which react only slowly it may bepreferred to use up to moles of sulphuric acid, and it is believed thatup to 40 moles is adequate in all cases.

The reaction temperature should not be greater than about 80C, asoxidative side reactions may occur, and preferably not greater than 60C.It is particularly preferred to operate at ambient temperatures below40C.

The reaction time required is a function of the skeletal structure ofthe reagents, the reaction temperature and the catalyst used, but itshould exceed one second. Reaction times of the order of one hour andmore may conveniently be used.

Di-neo acids may be used to make esters which are particularly useful assynthetic lubricant bases, for example. They are also useful in theproduction of polymers and plasticizers.

The invention is further illustrated in the following example:

EXAMPLE 1 2.2.7. trimethyl octanoic anhydride (0.7236 g, 2.04 mm) and 99percent sulphuric acid (5 g, 50 mm) were mixed and allowed to stand atca. 20C for 0.5h. The reaction mixture was treated with 4 volumes ofwater and the precipitated 2,2,7,7-tetramethyl suberic acid (m.p. 186C,wt. 0.100 g 2 0.44 mm :2l% yield) was isolated by filtration.

EXAMPLE 2 The use of neo-acid anhydride prepared from polyisomericneo-acids The neo-acid anhydride feed (b.p. 162l70C/5 mm) was preparedby the reaction of acetic anhydride and neo-tridecanoic acid prepared bya Koch synthesis based on propylene tetramer. The di-neo acid reactionprocedure was similar to that employed in Example 1 and the results aregiven below.

1. A process for the production of a dineo-dicarboxylic acid from2,2,7-trimethyloctanoic acid anhydride or neotridecanoic acid anhydriderespectively, which comprises bringing said anhydride in contact with atleast one molar equivalent of a strong acid selected from the groupconsisting of hydrofluoric acid, perchloric acid, chlorosulphonic acid,fluorosulphonic acid, phosphoric acid, sulphuric acid, pentafluoroantimonate to admixture with hydrofluoric acid, boron trifluoride inadmixture with phosphoric acid and boron trifluoride in admixture withhydro-fluoric acid at a temperature no higher than C.

2. A process according to claim 1 wherein the strong acid has a pK valuegreater than 2.

3. A process according to claim 1 wherein the acid is sulphuric acid ofat least w/w concentration.

4. A process according to claim 1 wherein l to 40 moles of acid are usedper mole of anhydride.

5. A process according to claim 1, wherein said anhydride is2,2,7-trimethyloctanoic acid anhydride and the dineo-dicarboxylic acidis 2,2,7,7-tetramethyl-suberic acid.

6. A process according to claim 5, wherein the acid is sulphuric acid ofat least 90% w/w concentration.

1. A process for the production of a dineo-dicarboxylic acid from2,2,7-trimethyloctanoic acid anhydride or neotridecanoic acid anhydriderespectively, which comprises bringing said anhydride in contact with atleast one molar equivalent of a strong acid selected from the groupconsisting of hydrofluoric acid, perchloric acid, chlorosulphonic acid,fluorosulphonic acid, phosphoric acid, sulphuric acid, pentafluoroantimonate to admixture with hydrofluoric acid, boron trifluoride inadmixture with phosphoric acid and boron trifluoride in admixture withhydro-fluoric acid at a temperature no higher than 80*C.
 2. A processaccording to claim 1 wherein the strong acid has a pK value greater than2.
 3. A process according to claim 1 wherein the acid is sulphuric acidof at least 90% w/w concentration.
 4. A process according to claim 1wherein 1 to 40 moles of acid are used per mole of anhydride.
 5. Aprocess according to claim 1, wherein said anhydride is 2,2,7-trimethyloctanoic acid anhydride and the dineo-dicarboxylic acid is2,2,7,7-tetramethyl-suberic acid.